Embodiments of the present invention relate generally to wireless communications, and more particularly, but not limited to, new types of communication formats and protocols for use in next generation wireless networks.
The fifth generation of mobile technology (5G) is positioned to address the demands and business contexts of 2020 and beyond, that is, to enable a fully mobile and connected society. Long Term Evolution (LTE) and New Radio (NR) systems are two terms relating to 5G development and are used interchangeably herein, and may include Carrier Aggregation (CA), where two or more Component Carriers (CCs) are aggregated in order to support wider transmission bandwidths. Secondary Cells (SCells) can be configured to form, together with a Primary Cell (PCell), a set of serving cells. To enable reasonable user equipment (UE) battery consumption when CA is configured, an activation/deactivation mechanism of SCells is supported with Media Access Control (MAC) Control Element (CE) signaling.
The 3GPP 5G Release 15 Technical Specification (TS) 38.331, titled: “NR; Radio Resource Control (RRC); Protocol specification,” published as ETSI TS 138 331 V15.2.1 (2018-06), and its content fully incorporated herein by its reference, provide details of new features in NR CA.
Radio resource control (RRC) is responsible for various control signaling including, connection control, initial security activation, radio configuration control including e.g. assignment/modification of ARQ configuration, HARQ configuration, DRX configuration, establishment/modification/release of radio bearers carrying user data (DRBs); and in case of CA, cell management including e.g. addition/modification/release of SCell(s), among others.
One new feature of NR CA includes the use of a Bandwidth Part (BWP), which is a mechanism to adaptively adjust UEs' operating bandwidth, where a UE is not required to transmit or receive outside of the configured frequency range of the active BWP, with an exception of measurement gap. The BWP is a frequency resource that the UE may use to receive and/or transmit; for example, a physical downlink shared channel (PDSCH)/physical uplink shared channel (PUSCH) may be scheduled within an active BWP. One BWP is limited to one cell, and Multiple BWPs may be configured per cell. For a UE in RRC connected state (“RRC_CONNECTED” state), an “active” BWP is the BWP presently used for transmission/reception. The number of BWPs are configured via the RRC, and only one BWP is selected as an active BWP, by using RRC signaling or via PDCCH/DCI signaling.
If a SCell utilizing BWPs is activated, a mechanism is needed to indicate which BWP is being activated. One solution is to first activate an SCell with MAC CE signaling, then use PDCCH/DCI signaling to specify the active BWP. However, a disadvantage of this solution is that it will require two separate steps/operations in time, which may cause additional latency for SCell with BWP activation. Embodiments of the present invention relate to various solutions for activating and/or deactivating SCells and their BWP with a lower latency than two sequentially performed steps, and with minimal complexity.